We have been studying tumor cell motility as a component of the process of metastatic dissemination. A number of autocrine motility factors (AMF's) have been shown to be synthesized by human tumor cells. These AMF's stimulate both directed and random motility in the same cells that produce the factor. Recently, we have purified a new AMF to homogeneity and have named this factor autotaxin (ATX). ATX is a basic glycoprotein with a molecular weight of 120,000 daltons and a pI of approximately 7.8. It stimulates pertussis-toxin sensitive motility in tumor cells when present at concentrations in the picomolar to nanomolar range. Anti-peptide antibodies, which recognize the protein in immunoblots, have been produced in rabbits. Oligonucleotides have been synthesized which correspond to the peptide sequences and have been used both as primers in polymerase chain reaction (PCR) amplifications and as probes to screen cDNA libraries made from the same melanoma cell line. In addition, we are continuing to characterize the protein and its active site by studies with endoglycosidases to identify the nature of the linked sugar moieties.